A wide variety of products are packaged in metal containers. Metal containers are desirable because they are durable and provide a distinctive appearance. Metal containers further can be formed in various shapes and sizes, and decorated with artwork. As a result, metal containers are often used to hold consumer products.
It is important that a metal container adequately retain the product it holds. Many products have a low viscosity, and therefore flow easily through cracks or seams in packaging. For example, products such as lotions, creams, and wax candles are heated during manufacture to obtain a flowable material which is processed and packaged more easily. Furthermore, products such as candles experience elevated temperatures when used for their intended purpose by the consumer, and therefore again create a flowable material. Metal containers used to hold those products must therefore be capable of retaining material having low viscosity.
Previously, glass jars and drawn metal containers have been used to hold easily flowable materials. Those conventional containers are typically formed as single, unitary pieces so that no seams are formed through which the material may leak. Production of these previous containers in varied shapes and sizes requires extensive machine retooling and therefore is overly time consuming and expensive. Furthermore, it is difficult to improve the appearance of these containers with artwork. Relatively deep drawn metal containers, for example, require artwork to be applied to a flat blank in distorted form so that, after the container is drawn into shape, the artwork is bent into the proper visual appearance. Layout and application of distorted artwork is, however, overly difficult and expensive.
Metal containers formed from multiple pieces are known which are less expensive to make in different shapes and sizes and easier to decorate. For example, a standard three-piece metal container has a base and side wall joined together to form the container, and a removable cover. The side wall is formed from a flat strip of metal that is then bent or rolled into a cylinder, square, or other shape, either regular or irregular. The ends of the side wall are joined to complete the shape. The base is generally flat and is formed to fit on a bottom edge of the side wall. Finally, the cover is a separate piece that is sized to removably fit over the top edge of the side wall.
Unfortunately, multiple piece metal containers create an increased risk of product leakage. From the above, it will be evident that a number of seams are formed between the different components of the three-piece metal container. A seam is formed at the side wall along the vertical height of the container where the opposite ends of the metal strip are joined. In addition, a seam is formed around the entire periphery of the side wall where it joins the base. As a result, materials having low viscosity may leak through the seams of the container.
Previous candle containers have employed various approaches to prevent leakage through container seams. Some containers, for example, have carefully formed seams which are tightly folded. The tight seams, however, are difficult to form and do not reliably prevent leakage. Other containers have used volatile or hazardous materials (such as methyl ethyl ketone(MEK)-based materials) to seal the container seams, and therefore pose a threat to the environment. Furthermore, these materials are typically applied to the container by hand (or "hand-doped") and therefore require expensive manual labor.
A downside of using metal containers to accommodate burning candles is well known and derives from the fact that the thermally conductive nature of metal frequently allows transmission of harmful quantities of heat from not only the flame but from the heated and sometimes liquefied candle wax, which heat passes through the container base to a support surface which maybe damaged, that is scorched by the heat.
Candle flash-over is also a danger. As is known, flash-over can occur when the pool of wax in the bottom of a candle container becomes relatively shallow, the wick bums down to approach the shallow pool and the pool becomes hotter than normal and ultimately reaches a self sustaining combustion temperature at which the wax will burn without a need for a wick. When this happens the candle container may reach temperatures significantly in excess of 600.degree. F. and thereby presents a significant fire hazard.
Pappas, U.S. Pat. No. 5,842,850 describes various approaches to preventing flash-over. These approaches deal primarily with keeping the wick, i.e. the source of candle ignition, sufficiently above the floor of the candle container which makes the flame go out before the fuel temperature exceeds its flash point. The '850 patent typically employs a candle wick sustainer wherein the wick is held in a bore formed in the sustainer. The bore which contains the wick is centrally disposed in vertical column that is supported by a base made impervious to candle fuel which thereby ensures that no candle fuel can reach the wick through the base that supports the bore containing the candle wick.
Because the wick must be in contact with the liquefied wax it burns, it follows that the height of the sustainer column determines when the wick will lose its supply of fuel. The '850 patent indicates that the top end of column extends above the floor of the candle container an amount sufficient to prevent flash-over. In several embodiments the '850 patent includes a centrally disposed pedestal upon which is mounted the afore described candle wick sustainer.
The subject invention distinguishes over the '850 patent in a number of novel and beneficial ways, most significantly in the provision of a sealed metal container, the sidewalls, side seam and base seam of which have been made hermetically secure while at the same time a stamp formed container base uniquely elevates a candle wick holder which functions to deprive the candle wick of burnable wax and prevents possible flash-over. At the same time the unique stamp formed container base isolates heated liquefied fuel to an outer periphery of the container bottom. The unique bottom structure also elevates the burning wick in such a manner that there is provided an insulating air space centrally disposed beneath the burning wick and a surface upon which the metal candle container rests.